The Big Bang happened around 13.7 billion years ago. This led to the creation of the entire universe.
We don't know what made the Big Bang possible or why it happened, we can only speculate. Was there even space and time before the Big Bang? We don't know this either.
The Big Bang provided us with raw materials for everything around us today.
After the Big Bang there was space which was quickly expanding. There was also time and matter and energy. The universe was so hot that you couldn't tell the difference between matter and energy. After the Big Bang, matter and energy separated.
Energy took different forms including gravity and electromagnetism. Matter appeared in the form of electrons and quarks. Quarks soon linked up to form neutrons and protons.
Something, we don't know what, contained everything needed to build our universe.